The Predictive Role of the Posterior Cerebellum in the Processing of Dynamic Emotions

Abstract

Recent studies have bolstered the important role of the cerebellum in high-level socio-affective functions. In particular, neuroscientific evidence shows that the posterior cerebellum is involved in social cognition and emotion processing, presumably through its involvement in temporal processing and in predicting the outcomes of social sequences. We used cerebellar transcranial random noise stimulation (ctRNS) targeting the posterior cerebellum to affect the performance of 32 healthy participants during an emotion discrimination task, including both static and dynamic facial expressions (i.e., transitioning from a static neutral image to a happy/sad emotion). ctRNS, compared to the sham condition, significantly reduced the participants’ accuracy to discriminate static sad facial expressions, but it increased participants’ accuracy to discriminate dynamic sad facial expressions. No effects emerged with happy faces. These findings may suggest the existence of two different circuits in the posterior cerebellum for the processing of negative emotional stimuli: a first-time-independent mechanism which can be selectively disrupted by ctRNS, and a second time-dependent mechanism of predictive "sequence detection" which can be selectively enhanced by ctRNS. This latter mechanism might be included among the cerebellar operational models constantly engaged in the rapid adjustment of social predictions based on dynamic behavioral information inherent to others’ actions. We speculate that it might be one of the basic principles underlying the understanding of other individuals’ social and emotional behaviors during interactions.

The effects of prefrontal tDCS and hf-tRNS on the processing of positive and negative emotions evoked by video clips in first- and third-person

“…It can be delivered from 0.1 to 640 Hz, or it can be used only at low (0.1-100 Hz) or only at high (100-640 Hz) frequency. It has been found that the application of high-frequency tRNS (hf-tRNS) positively modulates the excitability of motor and perceptual areas 62,63 , and also improves performance in behavioral tasks, for example in the domain of motor and visual perception learning 64,65 . To summarize, tES modulates cortical activity and in the present study, we exploited two different types of stimulation to investigate whether and in…”

“…Moreover, we also hypothesized that hf-tRNS modulates neuronal activity more than tDCS, as found in some fields different from emotions 64,82 , independently of hemispheric specialization possibly due to the importance of inter-hemispheric exchanges in correctly decoding both positive and negative emotions. Furthermore, a fundamental aspect of the present study consists in the specific set of stimuli used: to the best of our knowledge, this is the first study that used video stimuli to explore tES effects on emotional processing (positive results have been very recently described by applying tRNS on the cerebellum 62 ). The identified database also provides videos with neutral emotional valence, which were used in the study as control stimuli for those with positive and negative valence.…”